1.

A spring of force constant k is cut into two parts such that length of one part is double to another part. What will be the force constant of larger part?

Answer»

`(2)/(3)k`
`(3)/(2)k`
`3k`
`6k`

Solution :FORCE CONSTANT of SPRING is inversely PROPORTIONAL to its length,
`therefore k propto (1)/(l)`
`therefore kl = 1"""…….."(1)`
Given that `l_(1)= 2l_(2)`
and `l= l_(1)+l_(2)`
`=2l_(2)+l_(2)`
`l= 3l_(2)`
and `l= l_(1)+(l_1)/(2)= (3l_1)/(2)"""........."(2)`
Now, `k_(1)l_(1)= k_(2)l_(2) = kl`
`therefore k_(1)l_(1) = kl`
`k_(1)l_(1)= k xx (3l_1)/(2)` [From equation (1)]
`therefore k_(1)= (3)/(2)k`.


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